/*
* Copyright (c) 2013 Google, Inc.
*
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
#include "box2d/b2_particle_group.h"
#include "box2d/b2_particle_system.h"
#include "box2d/b2_world.h"

#if LIQUIDFUN_EXTERNAL_LANGUAGE_API
#include <Box2D/Collision/Shapes/b2CircleShape.h>
#endif //LIQUIDFUN_EXTERNAL_LANGUAGE_API

b2ParticleGroup::b2ParticleGroup()
{

  m_system = NULL;
  m_firstIndex = 0;
  m_lastIndex = 0;
  m_groupFlags = 0;
  m_strength = 1.0f;
  m_prev = NULL;
  m_next = NULL;

  m_timestamp = -1;
  m_mass = 0;
  m_inertia = 0;
  m_center = b2Vec2_zero;
  m_linearVelocity = b2Vec2_zero;
  m_angularVelocity = 0;
  m_transform.SetIdentity();

  m_userData = NULL;

}

uint32 b2ParticleGroup::GetAllParticleFlags() const
{
  uint32 flags = 0;
  for (int32 i = m_firstIndex; i < m_lastIndex; i++)
  {
    flags |= m_system->m_flagsBuffer.data[i];
  }
  return flags;
}

void b2ParticleGroup::SetGroupFlags(uint32 flags)
{
  b2Assert((flags & b2_particleGroupInternalMask) == 0);
  flags |= m_groupFlags & b2_particleGroupInternalMask;
  m_system->SetGroupFlags(this, flags);
}

void b2ParticleGroup::UpdateStatistics() const
{
  if (m_timestamp != m_system->m_timestamp)
  {
    float32 m = m_system->GetParticleMass();
    m_mass = 0;
    m_center.SetZero();
    m_linearVelocity.SetZero();
    for (int32 i = m_firstIndex; i < m_lastIndex; i++)
    {
      m_mass += m;
      m_center += m * m_system->m_positionBuffer.data[i];
      m_linearVelocity += m * m_system->m_velocityBuffer.data[i];
    }
    if (m_mass > 0)
    {
      m_center *= 1 / m_mass;
      m_linearVelocity *= 1 / m_mass;
    }
    m_inertia = 0;
    m_angularVelocity = 0;
    for (int32 i = m_firstIndex; i < m_lastIndex; i++)
    {
      b2Vec2 p = m_system->m_positionBuffer.data[i] - m_center;
      b2Vec2 v = m_system->m_velocityBuffer.data[i] - m_linearVelocity;
      m_inertia += m * b2Dot(p, p);
      m_angularVelocity += m * b2Cross(p, v);
    }
    if (m_inertia > 0)
    {
      m_angularVelocity *= 1 / m_inertia;
    }
    m_timestamp = m_system->m_timestamp;
  }
}

void b2ParticleGroup::ApplyForce(const b2Vec2& force)
{
  m_system->ApplyForce(m_firstIndex, m_lastIndex, force);
}

void b2ParticleGroup::ApplyLinearImpulse(const b2Vec2& impulse)
{
  m_system->ApplyLinearImpulse(m_firstIndex, m_lastIndex, impulse);
}

void b2ParticleGroup::DestroyParticles(bool callDestructionListener)
{
  b2Assert(m_system->m_world->IsLocked() == false);
  if (m_system->m_world->IsLocked())
  {
    return;
  }

  for (int32 i = m_firstIndex; i < m_lastIndex; i++) {
    m_system->DestroyParticle(i, callDestructionListener);
  }
}

#if LIQUIDFUN_EXTERNAL_LANGUAGE_API
void b2ParticleGroupDef::FreeShapesMemory() {
  if (circleShapes)
  {
    delete[] circleShapes;
    circleShapes = NULL;
  }
  if (ownShapesArray && shapes)
  {
    delete[] shapes;
    shapes = NULL;
    ownShapesArray = false;
  }
}

void b2ParticleGroupDef::SetCircleShapesFromVertexList(void* inBuf,
                             int numShapes,
                             float radius)
{
  float* points = (float*) inBuf;
  // Create circle shapes from vertex list and radius
  b2CircleShape* pCircleShapes = new b2CircleShape[numShapes];
  b2Shape** pShapes = new b2Shape*[numShapes];
  for (int i = 0; i < numShapes; ++i) {
    pCircleShapes[i].m_radius = radius;
    pCircleShapes[i].m_p = b2Vec2(points[i*2], points[i*2+1]);
    pShapes[i] = &pCircleShapes[i];
  }

  // Clean up existing buffers
  FreeShapesMemory();

  // Assign to newly created buffers
  ownShapesArray = true;
  circleShapes = pCircleShapes;
  shapes = pShapes;
  shapeCount = numShapes;
}
#endif // LIQUIDFUN_EXTERNAL_LANGUAGE_API
